The present invention relates in general to initiators for setting off detonation events, and in particular, to surface mount exploding foil initiators.
In various industries, such as mining, construction and other earth moving operations, it is common practice to utilize detonators to initiate explosives loaded into drilled blastholes for the purpose of breaking rock. In this regard, commercial electric and electronic detonators are conventionally implemented using hot wire igniters that include a fuse head as the initiating mechanism to initiate a corresponding explosive. Such hot wire igniters operate by delivering a low voltage electrical pulse, e.g., typically less than 20 volts (V), to the fuse head, causing the fuse head to heat up. Heat from the fuse head, in turn, initiates a primary explosive, e.g., lead azide, which, in turn, initiates a secondary explosive, such as pentaerythritol tetranitrate (PETN), at an output end of the detonator. Thus, conventional hot wire igniters cannot directly function a high density secondary explosive and must rely on an extremely sensitive primary explosive to transition the detonation process from the fuse head to a corresponding explosive output pellet.
An exploding bridgewire detonator (EBW) can serve as an alternative to the hot wire initiator. The EWB includes a short length of small diameter wire that functions as a bridge. In use, explosive material beginning at a contact interface with the bridgewire transitions from a low density secondary explosive to a high density secondary explosive at the output end of the detonator. The secondary explosive is normally PETN or cyclotrimethylene trinitramine (RDX). Like conventional hot wire initiators, an EBW cannot directly initiate a high density secondary explosive. To initiate a detonation event, a higher voltage pulse, e.g., typically, a threshold of about 500 V is applied in an extremely short duration across the bridgewire causing the small diameter wire to function the explosive material.